Don’t allow reachability for P2P / loopback

P2P may not need it, and loopback doesn’t make sense on iOS

Author: borrrden

src/Couchbase.Lite.Shared/API/Sync/Replicator.cs

@@ -484,9 +484,14 @@ private void StartReachabilityObserver()
                 return;   
             }
 
+            var remoteUrl = (Config.Target as URLEndpoint)?.Url;
+            if(remoteUrl == null) {
+                return;
+            }
+
             _reachability = Service.GetInstance<IReachability>() ?? new Reachability();
             _reachability.StatusChanged += ReachabilityChanged;
-            _reachability.Url = Config.RemoteUrl;
+            _reachability.Url = remoteUrl;
             _reachability.Start();
         }
 

src/Couchbase.Lite.Support.Apple/iOS/Support/iOSReachability.cs

@@ -104,7 +104,7 @@ public void Start()
         {
             _queue.DispatchSync(() =>
             {
-                if (_started) {
+                if (_started || Url?.IsLoopback == true) {
                     return;
                 }